package org.springframework.boot.web.servlet;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.Conventions;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

import javax.servlet.Registration;
import javax.servlet.ServletContext;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 * Base class for Servlet 3.0+ {@link javax.servlet.Registration.Dynamic dynamic} based
 * registration beans.
 *
 * @param <D> the dynamic registration result
 * @author Phillip Webb
 * @since 2.0.0
 */
public abstract class DynamicRegistrationBean <D extends Registration.Dynamic> extends RegistrationBean {

    private static final Log logger = LogFactory.getLog(RegistrationBean.class);

    private String name;

    private boolean asyncSupported = true;

    private Map<String,String> initParameters = new LinkedHashMap<>();

    /**
     * Set the name of this registration. If not specified the bean name will be used.
     * @param name the name of the registration
     */
    public void setName(String name) {
        Assert.hasLength(name,"Name must not be empty");
        this.name = name;
    }

    /**
     * Sets if asynchronous operations are supported for this registration. If not
     * specified defaults to {@code true}.
     * @param asyncSupported if async is supported
     */
    public void setAsyncSupported(boolean asyncSupported) {
        this.asyncSupported = asyncSupported;
    }

    /**
     * Returns if asynchronous operations are supported for this registration.
     * @return if async is supported
     */
    public boolean isAsyncSupported() {
        return asyncSupported;
    }

    /**
     * Set init-parameters for this registration. Calling this method will replace any
     * existing init-parameters.
     * @param initParameters the init parameters
     * @see #getInitParameters
     * @see #addInitParameter
     */
    public void setInitParameters(Map<String, String> initParameters) {
        Assert.notNull(initParameters,"InitParameters must not be null");
        this.initParameters = initParameters;
    }

    /**
     * Returns a mutable Map of the registration init-parameters.
     * @return the init parameters
     */
    public Map<String, String> getInitParameters() {
        return initParameters;
    }

    /**
     * Add a single init-parameter, replacing any existing parameter with the same name.
     * @param name the init-parameter name
     * @param value the init-parameter value
     */
    public void addInitParameter(String name,String value) {
        Assert.notNull(name,"Name must not be null");
        this.initParameters.put(name,value);
    }

    @Override
    protected final void register(String description, ServletContext servletContext) {
        D registration = addRegistration(description,servletContext);
        if (registration == null) {
            logger.info(StringUtils.capitalize(description) + " was not registered (possibly already registered?)");
            return;
        }
        configure(registration);
    }

    protected abstract D addRegistration(String description,ServletContext servletContext);

    protected void configure(D registration) {
        registration.setAsyncSupported(this.asyncSupported);
        if (!this.initParameters.isEmpty()) {
            registration.setInitParameters(this.initParameters);
        }
    }

    /**
     * Deduces the name for this registration. Will return user specified name or fallback
     * to convention based naming.
     * @param value the object used for convention based names
     * @return the deduced name
     */
    protected final String getOrDeduceName(Object value) {
        return this.name != null ? this.name : Conventions.getVariableName(value);
    }
}
